1. Field of the Invention
The present invention relates to portable computing devices and, more particularly, to charging batteries of portable computing devices.
2. Description of the Related Art
A computing device often includes one or more batteries to supply power to the computing device. Those computing devices that use batteries to supply power to operate are referred to as portable computing devices. Portable computing devices pertain to a wide range of devices, including portable computers (various sizes), portable game apparatuses, personal digital assistants (PDAs), etc.
Normally, these portable computing devices use rechargeable batteries as the primary source of power to the device. The portable computing devices typically are also able to couple to an alternating current (AC) power source with an AC adapter. The AC adapter plugs into a electric wall socket and converts incoming AC power into DC power which is used to power the portable computing device and/or charge the rechargeable batteries within the portable computing device.
Conventionally, these batteries take a considerable amount of time to fully charge. One reason is that the amount of power made available for charging is determined based on a worst case power budget such that the power used to charge a battery tends to be low. As such, the power used to charge the battery is low when the portable computing device is active. Another reason why conventional charging is so slow is that the amount of power varies over the charging cycle as the battery voltage changes but the charging current remain fixed at a safe level. With this approach, the fixed current level is set to a rather low level so that when the portable computing device is active it will not be starved for power by the charging of the battery. If the portable computing device were to be starved for power during its operation, then the portable computing device would fail, crash or otherwise cease to operate.
Thus, there is a need for charging techniques that are able to better utilize available power to charge batteries.